Chemical bonding Flashcards
what is a kernel?
Kernel: is the nucleus and all inner electrons
Octet rule
An element attain stability by have 8 electrons in its valance shell by sharing or complete transfer of electron
Drawbacks:
1. Element having atomic number less that 4 have unfilled electrons
2. Elements having d orbital are having extended octet
3. Some elements are having odd number of electrons
Noble gases like Xe and Kr form bonds
What was Kossel-Lewis method of representation of atoms?
With the symbol of the element and showing its valence shell electron using dots
Drawbacks:
1. didn’t give the shape, nature and energy levels of compound and molecules
Formal charge
method used foe balancing and keeping track of electrons in the molecule
FC = V - L - B
V = valence electrons
L = Lone pair
B = number of bonds
What are the main feature that define an ionic bond?
The main feature that define an ionic bond are:
1. Electron gain enthalpy: the energy releases or absorbed when electron is gained
2. Lattice enthalpy: the energy required to break one mole of bond into gaseous ions
Why do we need bond parameters?
Bond parameters are parameters that help define a bond thus they are important.
How is bond enthalpy and lattice enthalpy different?
Bond enthalpy deals with the amount of energy required to break one mole bond present in gaseous state
where as lattice enthalpy is the energy require to break one mole of bond to give gaseous ions
How is bond length and bond order related ?
Bond length is the length between the nuclei of two atoms where as bond order is the number of bond that atom is forming
Bond length increases bond order decreases
Bond angle
The angle formed between any two bonds. Depends on the compound
Resonance
Canonical structure: the representation of the same molecule in multiple way. (need one single bond and one double bond)
Resonance: different canonical structure lead to a formation of a hydride where the energy is less and that compound is more stable
Why is the resonance hybrid more stable that their canonical structures ?
This is because the hybrid averages the bond character
What results in the formation of a polar bonds?
Polar bonds are formed due to difference in electronegativity, because of there is is a distortion of electrons towards the more electronegative atoms creating a partials charge
Dipole moment
Charge * distance of separation
it is a vector quantity
Fajan’s Rules
No compound is purely ionic or covalent, they have the properties of both
- larger anion and smaller the cation more covalent
- more charge on the cation more covalent
- more polarizing cation and more polarizability of anion more covalent
What was the main principle behind the VSEPR theory?